Green Electronics Strategies – Reduce Power While Awake

Electronics Design To Save Energy

We have looked at how Low Power Electronics is a green strategy because it reduces the amount of power that has to be generated. And then we looked at a range of options for Reducing Electronics Power Consumption.

 

Now we are into specifics. The last post looked at Sleep Modes For Microcontrollers and how extending the Sleep Period and reducing the Sleep Current could dramatically Reduce Electronics Power Consumption.

 

 

Saving Electronics Power When Awake

The next logical step is to ensure that Power Consumption when awake is also reduced as much as possible. This can be a little tricky to get right as it can sometimes eliminate all the benefits you built up with you sleep strategy. The reasons for this are:

  • you can use Analogue Electronics to reduce software power requirements but it has to be turned off during Sleep Mode
  • if you do turn the power off to Analogue Electronics then there is a Settling Time after it is powered up
  • using Smart Electronics Chips can increase overall Quiescent Current
  • unless the Startup Time and Shutdown Time are quick, these can dominate the Power Consumption

Now there are some Software Architecture issues that affect these, especially the last one, but we will look at that in another post. For the last part of this post we will address the Electronics Design issues that have been raised here.

 

 

Electronics Design – To Save Power

Electronics Design can address these Power Consumption issues. Here is an example of a Power Consumption curve where an RC Time Constant must be taken into account to minimise average Power Consumption.

RC Time Constant affect Power Consumption

RC Time Constant affect Power Consumption

Here is a list of general strategies to select from to reduce Power Consumption:

  • using the lowest feasible Clock Rate so Clocked Devices use less power
  • using shorter Settling Times particularly by controlling RC Time Constants
  • select semiconductors for lowest overall Quiescent Current taking awake and sleep operation into account
  • ensure streamlined Startup and Shutdown operation

The overall Quiescent Current issues often gives the most difficulty. This can be addressed through Design Simulation either by SPICE, Software Modelling or a spreadsheet. For simpler systems the spreadsheet is often the easiest solution to implement. For very Software Intensive Systems the Software Modelling approach is the most reliable method. This will allow you to construct scenarios and be able to predict the Power Consumption implications for each of them.

 

For our Electronics Design and System Test methodology we often create a full system Software Model and so it is easy to use this same Software Model to accumulate the power consumption as it runs. This can also be automated and so simulate months of operation very quickly.

 

Next we will look at the role of Embedded Software in ensuring Power Consumption remains as low as possible.

 

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years. For more information go to his LinkedIn profile. This post is Copyright © Successful Endeavours Pty Ltd.

Green Electronics Strategies – Reducing Power Consumption

What is so good about Low Power Electronics?

If you read my last post, you would have noticed that this has the potential to reduce overall Power Requirements. Up until now, only Battery Operated Devices have really cared about Power Consumption. If you could plug it into a wall outlet then all was OK unless you were consuming more power than a standard circuit allowed.

 

Today, things are different. Climate Change is a global concern and reducing the Carbon Footprint for a product is important, regardless of what sort of power it consumes.

 

If we can reduce the Power Consumption of an appliance by 50%, then provided it’s Electronics Manufacture does not add that back again, we have a net Carbon Footprint gain. In fact, if we can do this across all products then we will meet our Global Carbon Reduction target of 50% by 2050 with this strategy alone.

 

 

How to reduce Electronics Power Consumption

This is not a new topic, and much of what I present here represents the combined experience of the Electronics and Embedded Software industry. Here is the short list:

  • reduce the Supply Voltage for Microcontrollers, Microprocessors and CMOS Circuits in general
  • use Sleep Modes and keep the Wake Periods as short as possible
  • replace High Power Consumption Devices with Low Power Consumption Devices
  • replace high utilisation Digital Filters with Analogue Electronics equivalents
  • replace Polled Operating Modes with Event Driven Operating Modes
  • use Low Power Smart Peripherals that Wake the rest of the System only when required
  • reduce the Time To Wake and the Time To Sleep
  • optimise the Software Execution Flow
  • use Energy Harvesting
  • Remove power from sections of Electronics Circuitry when not in use

There is overlap and interdependency between these but that is a good starting point.

 

Next I will start look at specific examples.

 

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years. For more information go to his LinkedIn profile. This post is Copyright © Successful Endeavours Pty Ltd.